Fredrick Art Glass makes replacement insulated glass panels to order We can provide both insulated and tempered glass for entry doors, side lights, replacement windows, skylights and any place where outside meets inside. This glass is available tinted, argon filled and low E. Please call Frederick Art Glass for details. What is insulated glass? Insulated glass consists of two panes of glass separated by a space. The perimeter of the glass is sealed, allowing no movement of outside air into the space. The space itself can be filled with dehydrated air, or with a special gas. The type of glass, the type of spacer, and the type of gas used in the space contribute to the overall insulating efficiency of the glass, and also the total cost.